I said that this statement is simply erroneous. What Ushiro Sensei teaches is not all kokyu, nor is what he does indistinguishable in that it is all kokyu.
OK, so Ushiro's much repeated comment and demonstrations and teachings involving "no kokyu, no Aikido" were meant to mean something else? I've just checked with some people who have been to a number of Ushiro's workshops (or classes where he taught) and I don't think anyone has a real quarrel with my comment except you. You, of course, now are in the position of calling Ushiro a personal teacher of yours and I don't want to get into a discussion where only a True Acolyte (tm) is permitted to discuss a teacher. So I pass.
You would like me to to now try and explain how you are wrong. You typically respond to direct inquiry from others about how do to things and how to gain a deeper understanding of things in a cagey manner without giving away details. Here is a good start for you. Kokyu is only one part of a foundational package.
Check the archives, Mark. I've posted more explanations, definitions, pictures with line drawings, etc., than anyone ever on this forum. What I refuse to do is to go into discussions that require at least a basic understanding of the process; hence, my informational posts have been restricted to what I thought might help people get started. And you know what? While those many posts of mine have helped academically for people to understand some of the processes, I haven't seen where it functionally did more than that, when some of these people came to workshops and showed what they could already do. I.e., there's a limit to what you can tell beginners.
On the other hand, I'm not a beginner. You are. I can follow any explanation you have to offer. I asked you to explain about Sanchin (which I practiced in Uechi Ryu karate) and, as an example, Tohei's training. If you can't explain it, you can't. Either explain it or say you can't. If you don't know the answer and we have the fact that Ushiro teaches Sanchin to Aikido people, then try to find some other factual (no ad hominem) method to approach the problem. If not, it appears that you just made a set of posts with no bearing to the discussion of the thread.